Prototype of a low-cost towed array with data-logging and short-range telemetry

Abstract

Passive Acoustic Monitoring studies have been benefited from open source software initiatives such as PAMGuard and ISHMAEL, but their widespread use is often limited by availability of low cost hardware. This work presents the design of a towed hydrophone array that can be built with off the shelf components. The system comprises a Raspberry Pi computer to log GPS, three-axis accelerometer, magnetometer, gyroscope, and audio from the hydrophone array (20 Hz-44 kHz). Data can be analyzed in PAMGuard, either in real time, through a short range (10 m) RF link, or retrieved later from the data logger. The array has been tested in La Paz bay Mexico, where semi-resident populations of long-beaked common dolphin (Delphinus capensis) and bottlenose dolphin (Tursiops truncatus) have been reported. Results and performance of the array in four modalities are presented; as a drift array, as a secondary array deployed from a small vessel, as an array towed by a Kayak, and as an array towed by an Autonomous Surface Veh...